The millions of air travelers that were stranded for a week during the 2010 Eyjafjallajokull eruption should avoid booking any getaways now that the ground is trembling at Bardarbunga, the centerpiece of the largest volcanic system in Iceland.

Heavy seismic activity kicked off this weekend, with the Icelandic Met Office subsequently reporting magma swelling near the surface and a string of earthquakes—including the strongest in the region since 1996. These worrisome signs prompted the government to issue this bulletin on Monday:

As evidence of magma movement shallower than 10 km implies increased potential of a volcanic eruption, the Bárðarbunga aviation color code has been changed to orange. Presently there are no signs of eruption, but it cannot be excluded that the current activity will result in an explosive subglacial eruption, leading to an outburst flood (jökulhlaup) and ash emission. The situation is monitored closely.

The code orange, still in effect in the region as of Wednesday night, means that the volcano is showing "heightened or escalating unrest with increased potential of eruption." Should an eruption happen, the government has said it might set up an exclusion zone measuring hundreds of miles around Bardarbunga to prevent its dust from destroying plane engines. The chance of that happening has spread bother far and wide: The British press reported it could cause "significant disruption" to vacation plans, and scientists say the travel mayhem could spread all the way over "northern Europe and the northern Atlantic."

The good news, however, is that Bardarbunga hasn't done much since making its rumbling entrance onto the world stage. Thousands of temblors show it to be locked in the grips of an earthquake swarm, according to the Met Office, but there have been no more indications of magma surging upward, a sign of imminent eruption. So there's a chance the volcano might just tremble and rage a bit before settling back down under its heavy glacial blanket.

But you don't have to wait for the next official bulletin to know what's happening at Bardarbunga. Bæring Gunnar Steinþórsson, an Icelandic programmer, has created a wonderful 3-D visualization of earthquakes at the volcanic site. The model displays the strength and timing of the quakes (yellow is oldest, red most recent), and can rotate to give a complete picture of the violence under the ground. Below is a screencap showing activity on Wednesday; head here for the interactive version.